It is a matter of experience. Some text books say 5 seconds before. If you see a gap in the traffic you may not have 5 seconds. In any case, you have to be sure that the people around you know what you intend to do. If they don't you may become a statistic.
When cycling, you should signal your intent to change direction by using your arm to point in the direction you plan to turn. This should be done a few seconds before the turn, and it's important to check for traffic before making the maneuver.
Drivers are required to signal at least 100 feet before changing directions. This gives other drivers and pedestrians enough time to anticipate the upcoming maneuver and react accordingly. Signaling well in advance helps improve overall road safety.
You should signal at least 100 feet before making a turn in urban areas and about 200 feet in rural areas. This allows other drivers and pedestrians adequate time to react to your intended maneuver. Always ensure that your signal is activated well in advance to promote safety and clear communication on the road.
You should turn on your turn signal before you need to brake for the turn.
When turning, you should give your turn signal at least 100 feet before the turn in urban areas and at least 500 feet before the turn on highways. This allows other drivers and pedestrians ample time to react to your intended maneuver. Always ensure your signal is activated well in advance to promote safety and clear communication on the road.
10 feet.
Signal well in advance.
To properly use the bike left turn signal while riding on the road, extend your left arm straight out to the side to indicate your intention to turn left. This signal should be given well in advance of the turn to alert other road users of your intended maneuver.
Drivers are required to signal a change of direction for at least 100 feet before turning or changing lanes. This allows other drivers to be aware of their intention and helps prevent accidents. Remember to turn off your signal after completing the maneuver.
mirror signal maneuver
When exiting a freeway, you should signal your intention to exit about 500 feet before the exit or approximately 5-10 seconds in advance, depending on your speed. This gives other drivers adequate notice of your maneuver and helps ensure a safer transition. Always check your mirrors and blind spots before changing lanes or exiting.
Approximately 1 block away from the desired turn